A method for exact and very precise treatment of surfaces is electrochemical reduction. In electrochemical reduction, the surface of the workpiece is generally processed using an electrode, and material is removed from the workpiece through electrochemical reaction of the workpiece with the electrolyte which is located between the workpiece and the electrode. In conventional methods of electrochemical reduction, the work is performed with gaps between the electrode and the workpiece which may be in the range of 1 mm to 2 mm. To produce finer structures and forms, the gap may be reduced to dimensions in the range of 10 μm to 50 μm and less.
In electrochemical reduction of this sort, the danger of an electrical contact between electrode and workpiece increases, as the electrode is brought closer to the workpiece. Such a contact would result in a local short circuit, which may result in damage both to the electrode and to the workpiece, so that not only the current workpiece but also subsequent workpieces may suffer from insufficient processing accuracy and precision, as well as insufficient stability of shape.
Methods are known in which detection of the distance between electrode and workpiece is determined by detecting the relationship between voltage and current during processing. In that case the occurrence of a short circuit should be prevented by electronic measures, in particular through appropriate regulation of the travel of the electrode. With a workpiece that exhibits local irregularities of the surface, in particular individual peaks that extend locally above the surface that is to be reduced, such regulation of the gap may fail and a local flashover may still occur. The associated damage to the electrode may also leave its mark on the workpiece being treated, even if the dimensions of the part in the short circuit situation were still sufficient.